A novel online auction system in which both sellers and buyers are compelled to bid their “true value”. Potential buyers solicit desired items or services and submit sealed bids. A demand curve is created based on buyer bids, and a potential seller can use the curve to create its own sealed bid. A winning seller is determined, however the system uses the bid of the second-lowest bidding seller to establish the ultimate group of winning buyers and sale price. Winning sellers can choose lower prices to capture higher sale quantities. Second or multiple transactions can be implemented from a single bid, if included in the winning set of bids.